It could be an easy fix like this or a bigger problem depending on the factors at play (are the joists accessible, will it mess anything else up if you just jack it up and reinforce, is there water damage or structural damage to the foundation causing the sag instead of just old joists, anything else going on like a supporting wall or posts under the floor, wiring or plumbing runs involved etc.).

For a 3,000 square foot house here is how much these “disasters” can costFoundation - up to $75,000Mold - Up to $150,000Termite damage - $40,000Structural issues - unfixable  

The only issue I had with them was several were missing hardware and shelves and some were damaged.

The end result is the non pet owners will end up paying a rent that supplements the pet owners due to increased risk (pet damage) requires increased income.  

They might also countersue you for damages or the judge might just award damages, because if you can't support your title claim then filing a spurious  lis pendens can be considered slander of title.

Here's a few online sources on the matter:The fact of the matter is, the landlord cannot “double-dip,” collecting full rent from one tenant, who has vacated, and collecting again from the new tenant.From: https://corealestateattorneys.com/breaking-a-colorado-residential-lease/In Colorado, landlords are usually required to mitigate damages if you move out of your rental before the lease is up.

We found out the property was broke into at 4 am yesterday and the newer furnace/ac were stolen along with some damage to the hardwood floors and the front door where they pried it open with a crow bar. 

(Question 1)My friends expressed concerns about Steve potential retaliation, maybe in ways that I might not be able to directly identify him for (e.g. causing damage to appliances in the common area and I would have no way of knowing who did it.)

Quote from @Jose Ramirez: I wonder if anyone can give me your feedback on umbrella insurance State Farm called me and told me that I should open a umbrella policy for my rental properties Most umbrella policies don’t cover business pursuits, nor losses from having too low damage coverage.

And you have no risk of evictions and, depending on your management company, you get most of your damages covered even.So I'm wondering if maybe investors just need to see the actual proformas and what these numbers look like with some basic assumptions (i.e. annual rent increases, annual appreciation) to really hit home how good these numbers truly are.